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Quantum Physics and Computers  [PDF]
Adriano Barenco
Physics , 1996, DOI: 10.1080/00107519608217543
Abstract: Recent theoretical results confirm that quantum theory provides the possibility of new ways of performing efficient calculations. The most striking example is the factoring problem. It has recently been shown that computers that exploit quantum features could factor large composite integers. This task is believed to be out of reach of classical computers as soon as the number of digits in the number to factor exceeds a certain limit. The additional power of quantum computers comes from the possibility of employing a superposition of states, of following many distinct computation paths and of producing a final output that depends on the interference of all of them. This ``quantum parallelism'' outstrips by far any parallelism that can be thought of in classical computation and is responsible for the ``exponential'' speed-up of computation. This is a non-technical (or at least not too technical) introduction to the field of quantum computation. It does not cover very recent topics, such as error-correction.
Quantum features of consciousness, computers and brain  [PDF]
Michael B. Mensky
Physics , 2009,
Abstract: Many people believe that mysterious phenomenon of consciousness may be connected with quantum features of our world. The present author proposed so-called Extended Everett's Concept (EEC) that allowed to explain consciousness and super-consciousness (intuitive knowledge). Brain, according to EEC, is an interface between consciousness and super-consciousness on the one part and body on the other part. Relations between all these components of the human cognitive system are analyzed in the framework of EEC. It is concluded that technical devices improving usage of super-consciousness (intuition) may exist.
A Prospect for Future Generation of Quantum Dots in Computers
Mirmansour Ziabari,Ahmad Mohades Kassai,Shahin Enayati Maklavani,Amirkoushyar Ziabari
Journal of Applied Sciences , 2008,
Abstract: In this study, first we described the different proposed design of QCAs and their functions. Then we described cell to cell interaction in the presence of external clocking voltage and finally we designed a 4-bit computer using a 4-bit processor which can be used as an 8-bit computer. This design study is based on this specification of 4-bit accumulator so that 8-bit data can be parallel processed in even and odd clock cycles. Our aim is to provide some evidences that quantum dot computers have the potential of increasing their word length and data capacity.
Quantum gravity computers: On the theory of computation with indefinite causal structure  [PDF]
Lucien Hardy
Physics , 2007, DOI: 10.1007/978-1-4020-9107-0_21
Abstract: A quantum gravity computer is one for which the particular effects of quantum gravity are relevant. In general relativity, causal structure is non-fixed. In quantum theory non-fixed quantities are subject to quantum uncertainty. It is therefore likely that, in a theory of quantum gravity, we will have indefinite causal structure. This means that there will be no matter of fact as to whether a particular interval is timelike or not. We study the implications of this for the theory of computation. Classical and quantum computations consist in ivolving the state of the computer through a sequence of time steps. This will, most likely, not be possible for a quantum gravity computer because the notion of a time step makes no sense if we have indefinite causal structure. We show that it is possible to set up a model for computation even in the absence of definite causal structure by using a certain framework (the causaloid formalism) that was developed for the purpose of correlating data taken in this type of situation. Corresponding to a physical theory is a causaloid, Lambda (this is a mathematical object containing information about the causal connections between different spacetime regions). A computer is given by the pair {Lambda, S} where S is a set of gates. Working within the causaloid formalism, we explore the question of whether universal quantum gravity computers are possible. We also examine whether a quantum gravity computer might be more powerful than a quantum (or classical) computer. In particular, we ask whether indefinite causal structure can be used as a computational resource.
Are there quantum bounds on the recyclability of clock signals in low power computers?  [PDF]
Dominik Janzing,Thomas Beth
Physics , 2002,
Abstract: Even if a logical network consists of thermodynamically reversible gate operations, the computation process may have high dissipation rate if the gate implementation is controlled by external clock signals. It is an open question whether the global clocking mechanism necessarily envolves irreversible processes. However, one can show that it is not possible to extract any timing information from a micro-physical clock without disturbing it. Applying recent results of quantum information theory we can show a hardware-independent lower bound on the timing information that is necessarily destroyed if one tries to copy the signal. The bound becomes tighter for low energy signals, i.e., the timing information gets more and more quantum.
More powerful biomolecular computers  [PDF]
Janusz Blasiak,Tadeusz Krasinski,Tomasz Poplawski,Sebastian Sakowski
Computer Science , 2011,
Abstract: Biomolecular computers, along with quantum computers, may be a future alternative for traditional, silicon-based computers. Main advantages of biomolecular computers are massive parallel processing of data, expanded capacity of storing information and compatibility with living organisms (first attempts of using biomolecular computers in cancer therapy through blocking of improper genetic information are described in Benenson et al.(2004). However, biomolecular computers have several drawbacks including time-consuming procedures of preparing of input, problems in detecting output signals and interference with by-products. Due to these obstacles, there are few laboratory implementations of theoretically designed DNA computers (like the Turing machine and pushdown automaton), but there are many implementations of DNA computers for particular problems. The first practical laboratory implementation of the general theoretical model of a machine performing DNA-based calculations was a simple two-symbol two-state finite automaton established by Benenson et al.(2001). In the present work, we propose a new attitude, extending the capability of DNA-based finite automaton, by employing two or potentially more restriction enzymes instead of one used in other works. This creates an opportunity to implement in laboratories of more complex finite automata and other theoretical models of computers: pushdown automata, Turing machines.
Ordinal computers  [PDF]
Ryan Bissell-Siders
Mathematics , 1998,
Abstract: Can a computer which runs for time $\omega^2$ compute more than one which runs for time $\omega$? No. Not, at least, for the infinite computer we describe. Our computer gets more powerful when the set of its steps gets larger. We prove that they theory of second order arithmetic cannot be decided by computers running to countable time.
Computers in Psychiatry  [cached]
Peter Lauritsen Lauritsen,Peter Elsass
Outlines : Critical Practice Studies , 2001,
Abstract: Within psychiatric research, the field of 'technotherapy' has been centred primarily on attempts to assess the computer as a treatment tool. The situation of daily clinical usage is, however, often ignored within such research, as for instance in controlled clinical trials. Our empirical study illustrates how health professionals and clients use different concepts of science and health in the attempts of formulating standards for using computers in psychiatric practice. The psychiatrists at a major psychiatric hospital decided and justified clients' use of computers on the basis of a 'techno-medical' quality assurance. At the same hospital the occupational therapists stressed the improvement of social relations as a treatment goal. And, at a psychiatric outside clinic the clients used concepts of 'normality' for articulating quality in computer use. Our study exemplifies how the use of computers is a multifaceted 'performance'. What is called for is a kind of research not limited by artificial borders of 'the context' and the 'user-perspective'. In much humanistic research as well as in action research concepts of 'context' and 'user-perspective' imply a somehow romantic view on practice as pure and uncontaminated by the outside world contrasted to a 'general' or an 'objective' way of knowing the world. These sharp distinctions were however difficult to maintain in our study, where health professionals and clients took local contingencies into account when they interpreted computer use, while they simultaneously drew on a socio-historical reservoir of resources.
Testing On Computers
Michael Russell
Education Policy Analysis Archives , 1999,
Abstract: Russell and Haney (1997) reported that open-ended test items administered on paper may underestimate the achievement of students accustomed to writing on computers. This study builds on Russell and Haney's work by examining the effect of taking open-ended tests on computers and on paper for students with different levels of computer skill. Using items from the Massachusetts Comprehensive Assessment System (MCAS) and the National Assessment of Educational Progress (NAEP), this study focuses on language arts, science and math tests administered to eighth grade students. In addition, information on students' prior computer use and keyboarding speed was collected. Unlike the previous study that found large effects for open-ended writing and science items, this study reports mixed results. For the science test, performance on computers had a positive group effect. For the two language arts tests, an overall group effect was not found. However, for students whose keyboarding speed is at least 0.5 or one-half of a standard deviation above the mean, performing the language arts test on computer had a moderate positive effect. Conversely, for students whose keyboarding speed was 0.5 standard deviations below the mean, performing the tests on computer had a substantial negative effect. For the math test, performing the test on computer had an overall negative effect, but this effect became less pronounced as keyboarding speed increased. Implications are discussed in terms of testing policies and future research.
COMPUTERS HAZARDS  [PDF]
Andrzej Augustynek
Studia Humanistyczne (Kraków. 2003) , 2007,
Abstract: In June 2006, over 12.6 million Polish users of the Web registered. On the average, each of them spent 21 hours and 37 minutes monthly browsing the Web. That is why the problems of the psychological aspects of computer utilization have become an urgent research subject. The results of research into the development of Polish information society carried out in AGH University of Science and Technology, under the leadership of Leslaw H. Haber, in the period from 2000 until present time, indicate the emergence dynamic changes in the ways of computer utilization and their circumstances. One of the interesting regularities has been the inverse proportional relation between the level of computer skills and the frequency of the Web utilization.It has been found that in 2005, compared to 2000, the following changes occurred:- A significant drop in the number of students who never used computers and the Web;- Remarkable increase in computer knowledge and skills (particularly pronounced in the case of first years student)- Decreasing gap in computer skills between students of the first and the third year; between male and female students;- Declining popularity of computer games.It has been demonstrated also that the hazard of computer screen addiction was the highest in he case of unemployed youth outside school system. As much as 12% of this group of young people were addicted to computer. A lot of leisure time that these youths enjoyed inducted them to excessive utilization of the Web. Polish housewives are another population group in risk of addiction to the Web. The duration of long Web charts carried out by younger and younger youths has been another matter of concern. Since the phenomenon of computer addiction is relatively new, no specific therapy methods has been developed. In general, the applied therapy in relation to computer addition syndrome is similar to the techniques applied in the cases of alcohol or gambling addiction. Individual and group therapy is carried out. In acute cases, pharmacology is applied as reinforcement of psychotherapy. Self-support groups are organised, in similarity to AA clubs for alcohol addicts.
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